Photochemistry of glycosyl azides-II

Trimethylsilylnitrate−Trimethylsilyl Azide: A Novel Reagent System for the Synthesis of 2-Deoxyglycosyl Azides from Glycals. Application in the Synthesis of 2-Deoxy-β-N-glycopeptides

A novel reagent system comprising Me(3)SiN(3) and 20 mol % of Me(3)SiONO(2) permits conversion of glycals to 1-azido 2-deoxy sugars in one step in fair to good yields. Galactals offer higher stereoselectivities than do the glucals. Reduction of the azide group with Ph(3)P-H(2)O to amino functionality followed by coupling with amino acids leads to the synthesis of novel 2-deoxy-beta-N-glycopeptides irrespective of the geometry of initial azido sugars. Using this protocol, a new gamma-sugar amino acid derivative is also procured.

Azide and Cyanide Displacements via Hypervalent Silicate Intermediates

Hypervalent azido- and cyanosilicate derivatives, prepared in situ by the reaction of trimethylsilyl azide or trimethylsilyl cyanide, respectively, with tetrabutylammonium fluoride, are effective sources of nucleophilic azide or cyanide. Primary and secondary alkyl halides and sulfonates undergo rapid and efficient azide or cyanide displacement in the absence of phase transfer catalysts with the silicate derivatives. Application of these reagents to the stereoselective synthesis of glycosyl azide derivatives is reported.

Reduction of azides under conditions of desorption-chemical ionization or fast-atom-bombardment mass-spectrometry

Under conditions of desorption-chemical ionization or fast-atom-bombardment mass-spectrometry, the azido groups in some carbohydrate derivatives and other substances undergo apparent reduction to amino groups. Experimental evidence is provided to corroborate the reduction, and possible explanations are proposed for the phenomenon.